| 摘要 |
PURPOSE:To provide an ultrasonic motor and an electronic apparatus including the ultrasonic motor with high performance, in which the rotational speed is controlled by detecting a rotational state of a moving body highly accurately. CONSTITUTION:After a vibration is generated by a piezoelectric transducer 12, a moving body 13 is rotated through frictional force with a vibrator 11. A gear part 13b of the moving body 13 is engaged with a tooth part of a pinion that rotates at a higher speed than that of the moving body 13. A rotating plate 111, which rotating with the pinion as a whole, has a plurality of slits 112. Light is emitted by a light source 19. The light passing through the slits 111 is cast to a light-receiving element 110. A detecting circuit 223 receives an output signal from the light-receiving element 110 and detects a passing speed through the slit 112. A change in angular velocity of the rotating plate 111 is calculated by an arithmetic circuit 224. While a control circuit is operated, a driving circuit applies a driving signal to a voltage oscillator 12 so that the moving body 13 rotates at an angular velocity previously set. |
